PLATE 12 
A. —This picture shows individual plant differences in resistance to the rootrots. 
The variety is Johnson County White Dent. Note the scattered, apparently 
normal stalks. The soil is typical of many of the average acid soils in Indiana. All 
gradations in growth of the stalks were found in this field; the poorer, stunted stalks 
are believed to have grown from infected seed. The largest differences in growth 
and yield between plants grown from infected and disease-free seed seem to occur 
in soils lacking in some essential nutrient or in which the aluminum and iron compounds 
occur in large available proportions. 
B. —The method used to introduce chemical solutions into the plants. The stalks 
were first punctured with a sharp cork borer, and the calcium-chlorid tubes were 
inserted tightly. Measured quantities of the solutions were placed in the tubes for 
absorption. 
